Daniel Thorburn

HOW MANY RANDOM DIGITS ARE REQUIRED UNTIL GIVEN SEQUENCES ARE OBTAINED

Random digits are collected one at a time until a given k-digit sequence is obtained, or, more generally, until one of several k-digit sequences is obtained. In the former case, a recursive formula is given, which determines the distribution of the waiting time until the sequence is obtained and leads to an expression for the probability generating function. In the latter case, the mean waiting time is given until one of the given sequences is obtained, or, more generally, until a fixed number of sequences have been obtained, either different sequences or not necessarily different ones. Several results are known before, but the methods of proof seem to be new.

Quality of life among Turkish immigrants in Sweden

ObjectivesTo assess quality of life among Turkish immigrants in Sweden by using the WHOQOL-100 scale and to evaluate the domains’ contribution to explain the variance in the quality of life of the immigrants. Our hypothesis was QOL among Turkish immigrants in Sweden are better than Turkish people who are living in their home country.Material and methodsThis study was performed in the districts of Stockholm where Turkish immigrants have mostly settled. With the help and guidance of the Turkish Association, a sample of 520 participants was selected. We collected the demographic data by printed questionnaires, and to measure the quality of life, we used the WHOQOL-100 scale Turkish version. For analysis, we used the SPSS V.13.0 and R package programs, variance analyses, and Bayesian regression.ResultsThe quality of life among the sample of Turkish immigrants was found to be moderate, but higher than the sample of the Turkish population. The quality of life of male immigrants was found to be higher than for females. Swedish-born Turks had better quality of life perceptions.ConclusionTurkish immigrants’ quality of life perceptions were better than those of the Turkish sample. The best scores were received from the third generation. The first generation and female immigrants need attention in order to receive higher quality of life perceptions.

Air quality in passenger cabins of DC‐9 and MD‐80 aircraft

Abstract The air quality in the passenger cabins of DC‐9 and MD‐80 aircraft has been studied on 48 representative flights. A portable air sampling case was used. No observations of health effects were made. The average levels of the components related to environmental tobacco smoke, were for respirable suspended particles 60, 250, 160 and 220 g/m3; for nicotine 5, 41, 21 and 32 g/m3; and for carbon monoxide 0.6, 1.1, 0.8 and 1.1 ppm in Business Non‐Smoking, Business Smoking, Tourist Non‐Smoking and Tourist Smoking sections respectively. The levels of carbon dioxide and relative humidity were about 1300 ppm and 25 percent in all sections respectively.

Turkish Immigrants in Sweden: Are They Integrated?

Many in Europe believe that large numbers of Turkish immigrants have failed to integrate into their host communities. How is this situation in Sweden? We found that most of the Turkish immigrants felt themselves to be Turkish and Sweden was accepted as a foreign country. Turkish-originated media was followed frequently and strong ties with relatives in Turkey were maintained. Marriage and friendship with native Swedes were not well accepted. We concluded that despite the multicultural aspects of Swedish integration policies, Turkish immigrants in Sweden were not well integrated and they prefer to live within the boundaries of their segregated, closed, small communities.

Genetic evaluation of mastitis liability and recovery through longitudinal analysis of transition probabilities

BackgroundMany methods for the genetic analysis of mastitis use a cross-sectional approach, which omits information on, e.g., repeated mastitis cases during lactation, somatic cell count fluctuations, and recovery process. Acknowledging the dynamic behavior of mastitis during lactation and taking into account that there is more than one binary response variable to consider, can enhance the genetic evaluation of mastitis.MethodsGenetic evaluation of mastitis was carried out by modeling the dynamic nature of somatic cell count (SCC) within the lactation. The SCC patterns were captured by modeling transition probabilities between assumed states of mastitis and non-mastitis. A widely dispersed SCC pattern generates high transition probabilities between states and vice versa. This method can model transitions to and from states of infection simultaneously, i.e. both the mastitis liability and the recovery process are considered. A multilevel discrete time survival model was applied to estimate breeding values on simulated data with different dataset sizes, mastitis frequencies, and genetic correlations.ResultsCorrelations between estimated and simulated breeding values showed that the estimated accuracies for mastitis liability were similar to those from previously tested methods that used data of confirmed mastitis cases, while our results were based on SCC as an indicator of mastitis. In addition, unlike the other methods, our method also generates breeding values for the recovery process.ConclusionsThe developed method provides an effective tool for the genetic evaluation of mastitis when considering the whole disease course and will contribute to improving the genetic evaluation of udder health.

Prediction of Single Episodes of Drinking During the Treatment of Alcohol-Dependent Patients

Drinking episodes during the treatment (relapses or lapses) of alcohol-dependent patients is predicted from clinical ratings of patients and individual background data such as alcohol drinking history and social status. The probability of these relapses (or lapses) is determined up to three days in advance using a logistic regression procedure. The study group consisted of 33 male alcohol-dependent persons, who participated in a treatment program. Clinical ratings were performed three times a week by a trained person during a visit to the clinic. The questionnaire contained 23 different items about irritation, craving for alcohol. sleep disturbances, etc. The relapses were either self-reported or detected by a biochemical marker in a urine sample that was taken daily. The most important factor for a relapse in alcohol drinking was shown to be if the patient already had had one relapse during the treatment. Other important clinical factors were the levels of irritation and autonomic disturbances. None of the variables measuring mood shifts was significant. Family conditions during childhood were the most important background variables. The predictions turned out to have a rather high specificity, but the sensitivity was lower. Half of the relapses were not predicted by an increased probability for relapse. Self-reported relapses were predictable from preceding interviews and were also less frequent compared to those detected objectively by the biochemical markers.

On the Effects of Malaria Treatment on Parasite Drug Resistance – Probability Modelling of Genotyped Malaria Infections

Abstract We compare the frequency of resistant genes of malaria parasites before treatment and at first malaria incidence after treatment. The data come from a clinical trial at two health facilities in Tanzania and concerns single nucleotide polymorphisms (SNPs) at three positions believed to be related to resistance to malaria treatment. A problem is that mixed infections are common, which both obscures the underlying frequency of alleles at each locus as well as the associations between loci in samples where alleles are mixed. We use combinatorics and quite involved probability methods to handle multiple infections and multiple haplotypes. The infection with the different haplotypes seemed to be independent of each other. We showed that at two of the three studied SNPs, the proportion of resistant genes had increased after treatment with sulfadoxine–pyrimethamine alone but when treated in combination with artesunate, no effect was noticed. First recurrences of malaria associated more with sulfadoxine–pyrimethamine alone as treatment than when in combination with artesunate. We also found that the recruited children had two different ongoing malaria infections where the parasites had different gene types.

The distribution of the record position and its applications

Abstract This is mainly an expository article on the positions of records in sequences of ordered elements. Such sequences are obtained, for example, when observing and ordering continuous iid random variables. In practice, records are of interest, for example, in meteorology and sports. A k-record is obtained when a new element is placed at position k counted from the top. The sequences of time points, when new k-records occur, are studied by elementary random walk methods. In the last section, it is shown that the time scale can be changed so that the time points of the k-records follow, approximately, a Poisson process.

On the mean number of trials until the last trials satisfy a given condition

Random variables are collected one at a time until the last k variables satisfy a given condition. The mean waiting time until this happens is studied and a general lemma is given. If the condition is satisfied by many possible stopping sequences the probability distribution of the k last variables is discussed. A fairly general treatment is given for the case when k = 2. Two other special cases are mentioned, viz. the case when the condition is defined by order relations between the last variables, and the case when the variables are discrete.

Effects of some Biological Covariates on the Probability of First Recurrence of Malaria following Treatment with Artemisinin Combination Therapy

Many investigations have shown that artemisinin-based combination therapies are effective in the treatment of uncomplicated malaria and that they do not increase parasite resistance to treatment as much as treatment with single substance. We study the relation between some biological covariates and the time to first recurrence of malaria for children treated for malaria in a clinical trial. One group received artesunate plus sulfadoxine-pyrimethamine and the other only sulfadoxine-pyrimethamine. We consider the event malaria-free for the first 42 (and 84) days. We use logistic regression models for the analyses. The main results show that the probability of no recurrence is higher if the parasite density in the blood is high. The results are inconclusive for other explanatory biological variables. The infecting parasites having genes that indicate resistance, gave different results at the two different treatment centres. There was no appreciable difference in the effects of treatment over the two follow-up periods and these treatments do not have any effect on the probability of a recurrence.